Inigo Martinez once pledged that he would never leave Real Sociedad for Athletic Bilbao.

Real Sociedad have moved on following the departure of their leading player and captain, Inigo Martinez, to bitter Basque rivals Athletic Bilbao this week and are asking their fans to do the same.

Athletic paid Martinez's €32 million release clause, a club record, and half of what they received from Aymeric Laporte's departure to Manchester City this week as well as offering the player double the wages earned at La Real.

From Arsenal's busy window to the Riyad Mahrez saga, the Exploding Heads run through all the major storylines from the January transfer window.

Get a quick recap of the biggest spenders in the Premier League during the January transfer window.

The winter window used to be something that happened in other leagues, but not this time. It might have been powered, at least in part, by the money than came from France and England -- almost €300 million arrived just from the sales of Neymar in the summer and Aymeric Laporte now -- but La Liga has been more active than ever before. Much, much more active.

Only Real Madrid, the traditional movers of the market, have not signed or sold a single player. Fifty-seven signings were made by...

Steve Nicol examines the state of Manchester City's back line and how Athletic Bilbao's Aymeric Laporte could be a positive addition.

Gab Marcotti shares his insights on Man City target Aymeric Laporte, Arsenal's interest in Pierre-Emerick Aubameyang and West Ham nearing a deal for Joao Mario.

After what had seemed a done deal to bring Alexis Sanchez to Manchester City, supporters could have been forgiven for feeling like this January transfer window was bit of a disappointment before Pep Guardiola broke the club's transfer record to make Athletic Bilbao centre-back Aymeric Laporte the latest addition to his squad for £57 million.

Real Sociedad are above Athletic Bilbao in La Liga but have only won one of the teams' last seven derbies.

It will all start around 11 o'clock on Saturday morning -- derby day -- at one of the most emblematic locations in central Bilbao. Athletic fans in red-and-white-striped shirts will confront Real Sociedad fans in blue and white and try to wind them up, get the better of them, by going through a catalogue of carefully-crafted put-downs of their rivals and eulogies of their own cause. When they've had a go, la Real's fans will have a go back. And so it will go, round and round, every line more pointed...

Which players are attracting attention in Europe's biggest leagues? Introducing Scouting Spotlight, looking at three players each week whose performances are making headlines ...

Joris Gnagnon -- Rennes

Hailing from Bondy, the northeastern suburb of Paris where Kylian Mbappe grew up, Gnagnon left it late to sign for a professional club, joining Rennes as an 18-year-old. He has since made up for lost time, establishing himself in the first-team at Roazhon Park last season and impressing in a...